Resnatron construction



H. J. D'AILEY June 24, 1958 RESNATRON CONSTRUCTION Filed Feb. 27, 1953 Unite RESN AT RON CONSTRUCTION Application February 27, 1953, Serial No. 339,219

Claims. (Cl. SIS-5.24)

In manufacture and use of resnatrons, wherein the resonators are generally within the evacuated region of the envelope, various problems are encountered of which cooling, tuning and maintenance of vacuum with bellows have been particularly diflicult of solution. For tuning purposes, there have been structures involving use of sliding joints, but with respect thereto it is necessary in the prior art to utilize a plurality of tunable cavities in order to obtain tuning over a wide tuning range where heavy radio frequency currents are involved. A single bellows for tuning over a wide frequency range is not usually practical.

According to the present invention, a resnatron construction is provided overcoming the afore-mentioned problems.

More specifically, the invention has for an object the provision of a tunable resnatron construction avoiding moving tuning mechanisms within the evacuated region.

Another object of the invention is to provide tuning means in a resonator of a resnatron exterior to the evacuated region.

A further object of the invention is to provide for tuning means for a resnatron movable over a long distance for tuning over a wide range.

Additional objects of the invention are to provide a structure which is conveniently fabricated and one which will provide a tuning means use of which will avoid development of pitting, burning or sticking of the tuning means where involved with heavy radio frequency currents.

Other objects of the invention will appear to persons skilled in the art to which it appertains as the description proceeds, both by direct recitation thereof and by implication from the context. 7

Referring to the accompanying drawing, in which like numerals of reference indicate similar parts throughout the several views:

Fig. 1 is a longitudinal sectional view of the essentials of a resnatron embodying the invention; and

Fig. 2 is a cross-section on line II-II of Fig. 1.

In the specific embodiment of the invention illustrated in said drawing, the reference numeral 19 designates an envelope in general, partly of glass and partly of metal, said envelope preferably being formed as a body of revolution and sealed and evacuated. One constituent part of said envelope, here shown at the lower part of the device, is a hollow metallic neck 11 having a bulbous hollow glass head 12 sealed peripherally of said neck back from one end of the neck so that said neck projects well into said head. In the opposite direction, said neck projects a greater distance from the head. These mentioned ends of the neck will be referred to herein as the inner and outer ends respectively. Said outer end provides both for support of a cathode assembly 13 coaxially therein and for efiecting an insulative seal for said neck and cathode assembly. Since, for conductive purposes, it is desirable to use copper as the particular metal for said neck, proper compensation for differentials rates Patent O "ice in expansion has to be made in effecting the seal. For that purpose, the seal shown includes a glass collar 14 having metal rings 15 at each end thereof. The upper one of these rings 15 is sealed by brazing or otherwise to the marginal end portion of the projecting outer end of said neck. The rings 15 are preferably an alloy such as described. in U. S. Patent No. 2,062,836 to Howard Scott and sold in the trade under the trademark Kovar, and the glass collar is a borosilicate glass such as also referred to in said patent. The lower end of the bottom one of said rings 15 is soldered or otherwise secured to a header 16 which underlies and mounts said cathode assembly 13. The lead-in wires 17 pass to the exterior through a glass press 18 having a Kovar ring attachment 19 to said header.

In the specific showing, the cathode assembly 13 is longer than said neck 11 and protrudes slightly at its inner end beyond said neck into the hollow of bulbous glass head 12. Said cathode assembly provides an electron emissive surface at said inner end. Opposite and parallel to said emissive surface and transverse to the axis of said cathode assembly 13 and neck 11, are two parallel plates 20, 21 having foraminous central grid portions in the areas of electron flow. Said plates are solid peripherally and project radially through the glass head 12 and provide exterior rims around the outside of said glass head insulated one from the other by the spacing and by the glass of said head intervening between and sealed to said plates. By the construction thus shown and described the cathode and foraminous grids are within the evacuated interior of the envelope and all have external connections.

Afore-mentioned neck 11 and cathode assembly 13 are coaxial with an annular space 23 therebetween. Also coaxially arranged, exterior to said neck is a cylindrical shell 24 the lower end of which has a transverse annular end or closure 25 soldered or otherwise secured at its inner periphery to the outside surface of said neck 114. near the outer end of said neck. The annular space he tween said shell and neck constitutes a cavity resonatoi, which, for distinguishing purposes will be referred to herein as cathode resonator 26. The upper end of said shell has an exterior flange 2'7 thereon which underlies the protruding margin of grid plate 20 and sealed thereto with an intervening insulating washer 28 of glass or other suitable material.

An annular tuning piston 29 is located in cathode resonator 26, and appropriate rods 30 protrude from the under side of said piston through the closure 25 for manual manipulation of the piston. It is appropriate to observe in this connection that the piston is in a nonevacuated region of the device and thus avoids the need for special seals or bellows as commonly employed in the prior art. Suitable resilient contact members or fingerr. 31 are provided at both peripheral edges of the piston so as to obtain desired electrical continuity between said piston and the shell 24 and neck 11.

At the far side of the grids from the cathode, the bulbous hollow head 12 extends across the electron path and forms a complete top wall 32 for the head so that no part of the device above said bulbous head needs to be evacuated. Said top wall 32 is dished or sags inward at its middle and receives therein the lower or inner end of an electrode 33 aligned with the cathode. Said electrode is shown as having a diameter equal to that of the cathode and has a convex end facing the end of the cathode. By applying appropriate potentials to the said electrode and cathode, electrons emitted from the cathode may be reflected by said electrode back toward the cathode and thereby caused to traverse the space between the grids for a second time. The convex curvature of said elecouter end thereof to which is secured a metallic ring 36, 7

preferably of the afore-mentioned Kovar in turn having a borosilicate glass collar 37 sealed thereto. Another ring 36 at the bottom end of the glass collar, sealed thereto, is in turn soldered or otherwise attached to the upper marginal end of said neck 34. The electrode and neck coaxially therearound are spaced radially and thus provide an annular space 38 therebetween.

Exterior to said neck 34 and coaxial therewith is a cylindrical shell 39 similar to and of equal diameter to afore-mentioned shell 24. The upper end of this shell 39 has a transverse annular end or closure 40 soldered or otherwise secured at its inner periphery to the outside surface of said neck at or near the outer end of said neck. The annular space between said shell and neck constitutes a cavity resonator, which in this instance for distinguishing purposes is termed the reflector resonator 41. The lower end of said shell 39 has an exterior flange 42 thereon which underlies the protruding margin of, grid plate 21 and sealed thereto with an intervening insulating washer 43 of glass or other suitable material.

As above described for the cathode resonator, the reflector resonator 41 also has a tuning piston 29 located therein, said piston having appropriate rods 30 protruding from the upper sides thereof through the shell closure 40 for manual manipulation of the piston. Here it can be pointed out that not only the reflector resonator is open to the air, but so also is the reflector electrode. Further carrying out the similitude of the reflector piston to the cathode piston, the same is provided with resilient contact members or fingers 31 at its inner and outer peripheries.

Other desirable microwave adjuncts may be utilized with the invention. For instance, each resonator is shown with a loop connector 44 therein as a terminal for a coaxial line 45 exterior to the resonator. Also chokes 46 are shown on the cathode assembly and on the reflector electrode.

What is claimed is:

1. A resnatron construction comprising a cathode assembly and an electron reflector in aligned opposition to each other, said electron reflector having an end portion, a sealed envelope for said cathode assembly, a wall of said envelope extending between said cathode assembly and said electron reflector, a first cavity resonator substantially surrounding said cathode assembly, a second cavity resonator substantially surrounding said reflector, said end portion of said electron reflector having a convex curvature in the direction of said cathode assembly.

2. A resnatron constructure comprising a cathode assembly and an electron reflector in aligned opposition to each other, said electron reflector having an end portion,

4 i a sealed envelope for said cathode assembly, a wall 0 said envelope extending between said cathode assembly and said electron reflector, a first cavity resonator substantially surrounding said cathode assembly, a second cavity resonator substantially surrounding said reflector, said end portion of said electron reflector having a convex curvature in the direction of said cathode assembly, a grid electrode transverse to said cathode assembly and said electron reflector and located between said cathode assembly and said electron reflector, said grid electrode being located within said sealed envelope.

3. A resnatron construction comprising a cathode assembly and an electron reflector in aligned opposition to each other, said electron reflector having an end portion, a sealed envelope for said cathode assembly, a wall of said envelope extending between said cathode assembly and said electron reflector, a first cavity resonator substantially surrounding said cathode assembly, a second cavity resonator substantially surrounding said reflector, said end portion of said electron reflector having a convex curvature in the direction of said cathode assembly, said first cavity resonator and said second cavity resonator being essentially exterior of said sealed envelope and tuning pistons in said resonators, said tuning pistons being located outside said envelope.

4. A resnatron construction comprising a cathode assembly and an electron reflector in aligned opposition to each other, said electron reflector having an end portion, a sealed envelope for said cathode assembly, a wall of said envelope extending between said cathode assembly and said electron reflector, a first cavity resonator substantially surrounding said cathode assembly, a second cavity resonator substantially surrounding said reflector, said wall of said envelope between said cathode assembly and said electron reflector being dished thereby forming a concavity in said wall and said end portion of said electron reflector being positioned within said concavity.

5. A resnatron construction comprising a cathode assembly and an electron reflector in aligned opposition to each other, said electron reflector having an end portion, a sealed envelope for said cathode assembly, a wall of said envelope extending between said cathode assembly and said electron reflector, a first cavity resonator substantially surrounding said cathode assembly, a second cavity resonator substantially surrounding said reflector, said end portion of said electron reflector having a convex curvature in the direction of said cathode assembly, said wall of said envelope between said cathode assembly and said electron reflector being dished thereby forming a concavity in said wall and said end portion of said electron reflector being positioned within said concavity.

References Cited in the file of this patent UNITED STATES PATENTS 2,196,392 Hansell Apr. 9, 1940 2,205,475 Hollmann June 25, 1940 2,376,882 Olken May 29, 1945 2,436,397 Morton Feb. 24, 1948 

